#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2020/9/21 17:37
# @Author : 吴敬超
# explain:
from compiler.ast import flatten
a=[[1,2],[5,6]]

listso=[]

listso=flatten(a)

print len(listso)
print "********************************"
for i in range(len(listso)):

    print i

    print listso[i]